OPINION: New Zealand First used to have this guy called Peter Brown as their deputy leader. Brown was (a) fiercely anti-immigration and (b) a migrant, having been born in the UK.

It was useful for Winston Peters, I think, to have a white migrant deputy thundering that "the wrong sort of people were coming into the country", spelling out to his elderly and easily bewildered constituency exactly what "the wrong sort" meant.

But here's the thing about Peters' perennial race-baiting – given airing most recently following a remit at the party's 25th birthday over the weekend. He campaigns on the immigration issue every election, but Peters has been in the powerbroker position in government three times now, and each of those governments has seen very high levels of net migration of what his supporters and voters consider "the wrong sort" of people.

There are a few reasons for this. Most populist, anti-migrant politicians believe what they say about "our values" and "preserving our way of life", and at least attempt to reduce migration when they get into office. Trump has his Muslim-ban; the conservatives have Brexit. But Peters' statements about migrants appear to be as meaningful as so much else he says, ie nothing. It is useful for him to race-bait by grandstanding about immigration but never useful for him to ever do anything about the issue.

He could probably make the government reduce its intake of non-white migrants, if he was so inclined: we've just seen the passage of the waka-jumping bill; it appears that Peters can get Labour and the Greens to do pretty much anything. But so long as his voters and the true-believers in his party never figure out the nature of his MO – and based on the interviews with New Zealand First delegates on last night's news, this is not a party of deep thinkers – there's no incentive for him to act.

On the contrary. New Zealand First's donors in the fishing and forestry sectors rely on high levels of migration to preserve a low-wage workforce working in high risk conditions. Maintaining those conditions is core business for Peters and Shane Jones. The people who pay for the party, who occupy the boardrooms of the fishing industry, are far more exacting than the suckers occupying the TV rooms of the retirement villages, who vote for it.

Migration also plays a key role in inflating our economic growth statistics. You can grow your economy either by increasing the skill of your workers, the worth of your companies, the value of the products they produce, or by simply letting lots of people into the country; New Zealand's political class has bet its chips on the second option. If a government reduces migration and the economy stops growing, or shrinks, that government will take a huge hit to its credibility as an economic manager and almost certainly be voted out.

So that's why we have a have an anti-immigration demagogue at the heart of government while the country simultaneously enjoys high levels of net migration. There's this theory that Winston Peters, despite his many terrible flaws, represents a lesser evil; that it's better to have him out there grifting the elderly racists, using their votes as currency to gratify his own malevolent ego than having some genuine ethno-nationalist form a new party and rise to power. "You'll miss him when he's gone," people warn me. They might be right. But I'm an optimist; I have faith in MMP's 5 percent threshold (which I used to oppose as undemocratic, but now see the wisdom of) to wipe Peters out in the next election and to protect us from his successors. New Zealand First is 25 years old, but it would, I think, be a great shame for our country if it lives to 30.